[Dovecot] Warning: Subscriptions file .. Removing invalid entry:

One of our dovecot-servers (v2.0.14) got a bit too busy last evening:

Sep 13 20:39:18 popimap1 dovecot: master: Warning: service(pop3-login): process_limit reached, client connections are being dropped

then logged a few:

Sep 13 20:39:20 popimap1 dovecot: pop3(XXXXXXXXX@YYYYY.YY): Warning: I/O leak: 0x3829233d20 (10)
Sep 13 20:39:20 popimap1 dovecot: pop3(XXXXXXXXX@YYYYY.YY): Warning: Timeout leak: 0x3829233ce0
Sep 13 20:39:20 popimap1 dovecot: pop3(ZZZZZ.ZZZZZ@ZZZZZZ.ZZ): Warning: I/O leak: 0x3829233d20 (10)
Sep 13 20:39:20 popimap1 dovecot: pop3(ZZZZZ.ZZZZZ@ZZZZZZ.ZZ): Warning: Timeout leak: 0x3829233ce0
Sep 13 20:39:20 popimap1 dovecot: pop3(YYYYYYY@YYYY.YYY): Warning: I/O leak: 0x3829233d20 (10)
Sep 13 20:39:20 popimap1 dovecot: pop3(YYYYYYY@YYYY.YYY): Warning: Timeout leak: 0x3829233ce0
Sep 13 20:39:20 popimap1 dovecot: pop3-postlogin: Error: Fatal: fd_send() failed: Broken pipe
Sep 13 20:39:20 popimap1 dovecot: pop3-postlogin: Error: Fatal: fd_send() failed: Broken pipe

and: Error: net_connect_unix(/var/run/dovecot/pop3-postlogin) failed: Resource temporarily unavailable

but what has me a bit worried is these:

imap(user@xxx.xxx): Warning: Subscriptions file /path/to/user@xxx.xxx/subscriptions: Removing invalid entry: .Sent
imap(user@xxx.xxx): Warning: Subscriptions file /path/to/user@xxx.xxx/subscriptions: Removing invalid entry: .Spam
imap(user@xxx.xxx): Warning: Subscriptions file /path/to/user@xxx.xxx/subscriptions: Removing invalid entry: .Drafts
imap(user@xxx.xxx): Warning: Subscriptions file /path/to/user@xxx.xxx/subscriptions: Removing invalid entry: .Trash

which happened for a two users during this high load periode. Looking at their mail directory I can't see why these should be invalid? They're there, has sane permissions and contains messages..

-jf